Question asked 2018-01-26 12:11:23 ...
Most recent comment 2018-06-05 10:36:46
Hi, I've sometimes used cradled birch plywood panels for smaller works (from 4"x5" up to 11"x14") over the past 5 years. I size the panels on all surfaces with an acrylic medium (GAC100) and prime the face with 4 coats of acrylic gesso. The brand of panel I use seems to be of good quality. There is no raising of fibers when I size them. However, I've seen some instances of people on painting forums implying that plywood panels will "definitely" crack over time - no exceptions - and shouldn't be used. How accurate is that assertion in your estimation? The article at: http://www.justpaint.org/understanding-wood-supports-for-art-a-brief-history/ says " Completely sealing and priming the plywood with several layers of gesso is essential to eliminate future cracking ... " This implies that, with proper preparation, plywood panels are a viable long term support. Am I correct in that assumption?
Answers and Comments
I would not contradict those at Golden as they tend to do
substantial experimentation before making claims about performance. What they
state is certainly true, it is important to follow those steps to create a
panel that is less likely to develop cracks or checks. I would add though, in
my experience and years of examining paintings and student works, it is extremely
common to see some degree of checking in grounds (acrylic dispersion and glue
based) on ply panels (when there is no interlayer of fabric or film). Plywood
is made by basically shaving wood off of the trunk of a tree to produce a very
long continuous sheet (sort of like a roll of toilet paper). This sheet is cut,
flattened, and adhered, to another sheet, usually at a 90-degree angle. This creates
a panel that is far less likely to warp but this flattening does introduce stresses
that tend to reappear as checking along the grain. A well-sealed ply panel with
a substantial acrylic dispersion ground layer may not develop these defects. Additionally
acrylic dispersion grounds are far more flexible than glue grounds and would
likely show less checking than glue-based grounds.
However, even for acrylic dispersion grounds, I tend to
recommend gluing a fine fabric to the sized panel, applying an additional layer
of size on top of the fabric after it has dried, and put the acrylic dispersion
ground on the fabric layer. This resembles the methods used by the Early
Italian tempera painters to diminish cracking in their true gesso grounds on
panel. Others may have a different take on this.
Thanks Brian, but this happens to actually be a case where questioning us might be in order! I feel I can share that we are actively looking at changing our stance on plywood, or at least modifying it, and are just now plotting to do some testing and more thorough research. And, while the referenced article was published in Just Paint, our newsletter, the research and views were from Elaine Salazar, of Ampersand, who certainly has a long relationship to these issues and materials, thus we would continue to give them some consideration and weight. That said a few things have started to chip away at our own confidence in plywood. One, is having some cases come to us with cracking in the ground and paint layers that seemed clearly associated with the veneer used on the underlying ply. Second, a comment from an conservation scientist we were corresponding with caught our attention when they stated they felt that plywood was unsuitable for permanent works of art, and finally - while we rarely give Wet Canvas posts a lot of weight as a reference - this following one felt exceptionally well researched in terms of citing conservation research and studies from the Forrest Products Laboratory, and the points made are in line with your own comments above:
So, all of that combined definitely has us taking a renewed look at alternatives, such as other types of composite, engineered wood supports, and of course aluminum composite panels remain seemingly ideal. We should also mention that internally we rely on MDO (medium density overlay) for our plywood supports, as do several of us in our own work. The resin impregnated paper surface does seem to solve some of the issues of grain and provides a smooth surface, but even there I think more research might be warranted, even though it appears to pass muster as an approved material for use in storage cases in museums.
Anyway, wanted to chime in on that one aspect at least.
One more thing. While many people seem to assume that GAC 100 or acrylic gesso somehow seal the surface of a panel, they are actually really poor moisture barriers, which is precisely what you want to try to have on those exposed sides. For that we would recommend following our guidelines in the following article on Preparing Panels for a Life Outdoors
Although the focus is on exterior use, it would still represent a superior moisture barrier to many alternatives. You might also, for interior use, take a look at pigmented shellac primers, such as BIN. See my posting in a different MITRA thread on sealing hardboard with shellac for some references to support that option:
Okay, hope that helps.
This Page Last Modified On: